This invention relates generally to devices and methods for shaping tissue by deploying one or more devices in body lumens adjacent to the tissue. One particular application of the invention relates to a treatment for mitral valve regurgitation through deployment of a tissue shaping device in the patient's coronary sinus or great cardiac vein.
The mitral valve is a portion of the heart that is located between the chambers of the left atrium and the left ventricle. When the left ventricle contracts to pump blood throughout the body, the mitral valve closes to prevent the blood being pumped back into the left atrium. In some patients, whether due to genetic malformation, disease or injury, the mitral valve fails to close properly causing a condition known as regurgitation, whereby blood is pumped into the atrium upon each contraction of the heart muscle. Regurgitation is a serious, often rapidly deteriorating, condition that reduces circulatory efficiency and must be corrected.
Two of the more common techniques for restoring the function of a damaged mitral valve are to surgically replace the valve with a mechanical valve or to suture a flexible ring around the valve to support it. Each of these procedures is highly invasive because access to the heart is obtained through an opening in the patient's chest. Patients with mitral valve regurgitation are often relatively frail thereby increasing the risks associated with such an operation.
One less invasive approach for aiding the closure of the mitral valve involves the placement of a tissue shaping device in the cardiac sinus and vessel that passes adjacent the mitral valve. The tissue shaping device is designed to push the vessel and surrounding tissue against the valve to aid its closure. This technique has the advantage over other methods of mitral valve repair because it can be performed percutaneously without opening the chest wall. Examples of such devices are shown in U.S. patent application Ser. No. 10/142,637, “Body Lumen Device Anchor, Device and Assembly” filed May 8, 2002; U.S. patent application Ser. No. 10/331,143, “System and Method to Effect the Mitral Valve Annulus of a Heart” filed Dec. 26, 2002; and U.S. patent application Ser. No. 10/429,172, “Device and Method for Modifying the Shape of a Body Organ,” filed May 2, 2003. The disclosures of these patent applications are incorporated herein by reference.
When deploying a tissue shaping device in a vein or artery to modify adjacent tissue, care must be taken to avoid constricting nearby arteries. For example, when treating mitral valve regurgitation, a tissue shaping device may be deployed in the coronary sinus to modify the shape of the adjacent mitral valve annulus. Coronary arteries such as the circumflex artery may cross between the coronary sinus and the heart, however, raising the danger that deployment of the support may limit perfusion to a portion of the heart by constricting one of those arteries. See, e.g., the following applications, the disclosures of which are incorporated herein by reference: U.S. patent application Ser. No. 09/855,945, “Mitral Valve Therapy Device, System and Method,” filed May 14, 2001 and published Nov. 14, 2002, as US 2002/0169504 A1; U.S. patent application Ser. No. 09/855,946, “Mitral Valve Therapy Assembly and Method,” filed May 14, 2001 and published Nov. 14, 2002, as US 2002/0169502 A1; and U.S. patent application Ser. No. 10/003,910, “Focused Compression Mitral Valve Device and Method” filed Nov. 1, 2001. It is therefore advisable to monitor cardiac perfusion during and after such mitral valve regurgitation therapy. See, e.g., U.S. patent application Ser. No. 10/366,585, “Method of Implanting a Mitral Valve Therapy Device,” filed Feb. 12, 2003, the disclosure of which is incorporated herein by reference.